Project Number: 5070-12130-006-17-N
Project Type: Non-Funded Cooperative Agreement
Start Date: Sep 1, 2019
End Date: Aug 31, 2022
The goal of the project is to incorporate factors that account for the depth of a restrictive layer and rainfall intensity into the Soil Vulnerablity Index (SVI) ruleset. The objectives are to: - Propose changes to the SVI to account for the depth of a restrictive layer, - Propose changes to the SVI to account for rainfall intensity, and - Evaluate all changes on the 13 CEAP watersheds considered in the previous SVI evaluation.
Objective 1: Propose changes to the SVI to account for the depth of a restrictive layer. a) Review the 13 CEAP watersheds to identify areas which have known restrictive layers that influence soil-water infiltration. Data and working relationships from the previous SVI project will be employed to expedite the review. b) Review modeling data and expert knowledge to propose combinations of depth to the restrictive layer and slope that increase or decrease the vulnerability to runoff or to leaching. c) Propose changes to the SVI that account for the effect of restrictive layers on surface runoff and water infiltration. d) Evaluate the SVI vulnerability classification based on the revised SVI in those regions where restrictions are present. Objective 2: Propose changes to the SVI to account for rainfall intensity. Task 1: Review annual and seasonal rainfall characteristics in those regions represented by the 13 CEAP watersheds. Task 2: Develop distributions of rainfall rate and rainfall energy based on historical precipitation records and representative of selected return periods and probabilities. Task 3: Evaluate modifications to the SVI vulnerability classification based on rainfall rate levels on a seasonal and annual basis. Inclusion of some aspect of rainfall energy will also be attempted. Task 4: Evaluate the improvement in SVI vulnerability classification based on the revised SVI using rainfall rate information from the respective 13 CEAP watersheds. The ARS PI, Cooperator, and NRCS SVI developers will have regular meetings to discuss research and data analysis methods, interpretation of results, and updates to the SVI classifications based on agency revisions from this and other studies.